A band gap reference circuit (hereinafter referred to as “a BGR circuit”) is known as a reference current generation circuit. The BGR circuit compensates temperature characteristic using a combination of a PN-junction diode having a positive temperature characteristic and a resistor having a negative temperature characteristic. Japanese Patent Application publication JP 2007-200233 discloses an example of such a BGR circuit.
The BGR circuit can compensate a first-order temperature coefficient without difficulty, but has an issue that the BGR circuit is difficult to compensate a second-order temperature coefficient.
This is because the temperature characteristic of the resistor is linear whereas the temperature characteristic of the PN-junction diode is non-linear, and because a reference current having a positive second-order temperature coefficient corresponding to a reference current having a negative second-order temperature coefficient can not easily obtained.
Accordingly, in the BGR circuit, the linearity of the reference current is bad with respect to the temperature so that a desired characteristic can not be obtained. For example, in an integrated circuit called System on Chip (SoC) in which various functions are integrated into one chip, a high degree of linearity with respect to a temperature is required for a reference current, with high-performance signal processing by the SoC.